Sagarin, like the developers of many other sports rating systems, does not divulge the exact methodology behind his system. He offers two rating systems, each of which gives each team a certain number of points. One system, "Elo chess," is presumably based on the Elo rating system used internationally to rank chess players. This system uses only wins and losses with no reference to the victory margin. The other system, "Predictor," takes victory margin into account. For that system the difference in two teams' rating scores is meant to predict the margin of victory for the stronger team at a neutral venue. For both systems teams gain higher ratings within the Sagarin system by winning games against stronger opponents, factoring in such things as home-venue advantage. For the Predictor system, margin of victory (or defeat) factors in also, but a law of diminishing returns is applied. Therefore, a football team that wins a game by a margin of 7-6 is rewarded less than a team that defeats the same opponent under the same circumstances 21-7, but a team that wins a game by a margin of 35-0 receives similar ratings to a team that defeats the same opponent 70-0. This characteristic has the effect of recognizing "comfortable" victories, while limiting the reward for running up the score.